[PDF] Effects Of Polymer Parameters On Drag Reduction eBook

Author : Robert H. Wade
Publisher :
Page : 39 pages
File Size : 45,60 MB
Release : 1975
Category :
ISBN :

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The effects of three molecular parameters on drag reduction were studied under turbulent-flow conditions. Drag reduction capability of linear polymers is altered by branching. Many short side chains decrease efficiency, while fewer but long branches increase it. The drag reduction of polyelectrolytes can be reversibly destroyed or enhanced by changes in configuration resulting from changes in pH or ionic strength or by complexing with counter-ion polyelectrolytes. Cross-linking can enhance or destroy the drag-reducing capability of a linear molecule, depending on the degree of cross-linking. Polymer degradation in turbulent flow is somewhat less in branched and cross-linked molecules than in linear ones.

Author : Feng-Chen Li
Publisher : John Wiley & Sons
Page : 233 pages
File Size : 14,3 MB
Release : 2012-01-10
Category : Science
ISBN : 1118181115

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Turbulent drag reduction by additives has long been a hot research topic. This phenomenon is inherently associated with multifold expertise. Solutions of drag-reducing additives are usually viscoelastic fluids having complicated rheological properties. Exploring the characteristics of drag-reduced turbulent flows calls for uniquely designed experimental and numerical simulation techniques and elaborate theoretical considerations. Pertinently understanding the turbulent drag reduction mechanism necessities mastering the fundamentals of turbulence and establishing a proper relationship between turbulence and the rheological properties induced by additives. Promoting the applications of the drag reduction phenomenon requires the knowledge from different fields such as chemical engineering, mechanical engineering, municipal engineering, and so on. This book gives a thorough elucidation of the turbulence characteristics and rheological behaviors, theories, special techniques and application issues for drag-reducing flows by surfactant additives based on the state-of-the-art of scientific research results through the latest experimental studies, numerical simulations and theoretical analyses. Covers turbulent drag reduction, heat transfer reduction, complex rheology and the real-world applications of drag reduction Introduces advanced testing techniques, such as PIV, LDA, and their applications in current experiments, illustrated with multiple diagrams and equations Real-world examples of the topic’s increasingly important industrial applications enable readers to implement cost- and energy-saving measures Explains the tools before presenting the research results, to give readers coverage of the subject from both theoretical and experimental viewpoints Consolidates interdisciplinary information on turbulent drag reduction by additives Turbulent Drag Reduction by Surfactant Additives is geared for researchers, graduate students, and engineers in the fields of Fluid Mechanics, Mechanical Engineering, Turbulence, Chemical Engineering, Municipal Engineering. Researchers and practitioners involved in the fields of Flow Control, Chemistry, Computational Fluid Dynamics, Experimental Fluid Dynamics, and Rheology will also find this book to be a much-needed reference on the topic.

Author : R. R. Walters
Publisher :
Page : 66 pages
File Size : 17,9 MB
Release : 1974
Category : Diffusion in hydrology
ISBN :

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The effect of polymer molecular weight on turbulent diffusion and drag-reduction was investigated over a uniformly distributed polymer injection area. The purpose of the experiments, carried out in a porous wall pipe flow facility, was to determine optimum values of polymer molecular weight and injection mass flux for attaining maximum skin-friction reduction over a distributed injection area and to investigate associated turbulent diffusion characteristics. It was found for this type of polymer supply system, which provided polymer directly to the required wall shear stress region, that the optimum molecular weight was approximately an order of magnitude less than that normally used in skin-friction reduction applications with homogeneous solutions and localized injection ...Abstract, p. iii.

Author : Stanley M. Kumor
Publisher :
Page : 618 pages
File Size : 12,89 MB
Release : 1973
Category :
ISBN :

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The primary objective of an experimental investigation was to study the effect that a drag-reducing polymer has on the turbulent boundary layer of a submerged flat plate using a Laser-Doppler flowmeter. Data are presented showing the time effects caused by polymer solution drag-reduction degradation on the mean velocity and axial fluctuating-velocity profiles. The importance of the data is that it provides a connection between the apparently diverse results reported previously for the velocity profiles at conditions of high and low drag-reduction effectiveness. The polymer molecules' effect on the boundary layer structure is apparently progressively restricted to the near wall region with decreasing drag reduction in agreement with the mean velocity profiles. (Author).

Author :
Publisher :
Page : 121 pages
File Size : 29,73 MB
Release : 1966
Category :
ISBN :

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Tube flow data indicate that the drag reduction of high molecular weight polymer solutions decreases in an orderly fashion with inc.eased molecular coiling of the polymer. A correlating equation for this effect is presented. For three polymers at four concentrations the maximum drag reduction was obtained at temperatures less than 105F and at 140F solutions of all three polymers suffered a decrease in drag reduction. A graphical relationship is presented that qualitatively correlates the variation of viscosity and drag reduction caused by a variation in temperature. A decrease in drag reduction occurs if low concentration of high molecular weight polymers are subjected to steady state turbulent tube flow. A slow decrease in viscosity of high molecular weight solutions due to physical adsorption on the solid surfaces in glassware as well as chemical degradation during static storage can be mitigated by adding isopropanol or using deionized water. The average molecular weight of different samples of the same polymer can vary by as much as 50 percent. (Author).